I have a question concerning Psychophysiological (PPI). I have two groups and one (Group A) activates the inferior frontal gyrus (IFG) much more than the other.

When I perform PPI having the IFG as seed, group A positive and negative connections are fewer and less strong than in group B.

I wanted to explore why this is the case? How can explore if the variance in the BOLD activity in IFG in group A is really low, that could lead to reduced functional connectivity? Or is there anything else I should explore?